REUSE OF TREATED EFFLUENT AS COOLING TOWER MAKEUP AT A MULTI-BUSINESS COMPLEX

This paper describes a case history of a state-of-the-art sequencing batch reactors (SBR) and effluent polishing system from which water will be reused in a multi-business complex's cooling towers. Increased production and expansions in all three site businesses (crop protection products, electronic materials and pharmaceuticals) have resulted water supply as well as site discharge flow restrictions. A site-wide water survey and flow balance identified reuse of treated effluent as makeup in the cooling water systems as the greatest opportunity for fresh water conservation and discharge flow reduction. Treatability studies were completed for the technology selection and design of the integrated treatment/effluent polishing system. Weak-acid cation (WAC) resin ion exchange was selected as the primary polishing technology from alternatives evaluated. (found to be both effective and simple compared to other processes). The WAC resin reduced both hardness and alkalinity as well as removed silica in a single-stage process.This case history describes the evaluations that led to the overall plan for reusing treated wastewater in the industrial complex's cooling towers to replace fresh water makeup. The new wastewater treatment system has a design capacity of 225,000 gal/day (35.5 m3/hr) with a target recovered water flow of 173,000 gal/day (27.3 m3/hr). Up to 77% of the site's effluent will then be recovered and reused as cooling tower makeup resulting in a 45% reduction in future fresh water consumption for the complex. This integrated water/ wastewater treatment system is an excellent example of maintaining sustainable development of a multi-business industrial complex.